AUSTIN -- As Congress debates immigration reform, the congressman who represents the longest stretch of border in the country is calling on the Texas comptroller to again study the economic impact of illegal immigration.

U.S. Rep. Pete Gallego, D-Texas, last week called on Texas Comptroller Susan Combs to repeat a study that, the first time it was done, produced results that were unexpected by many.

In 2006, then-Comptroller Carol Keeton Strayhorn determined that if Texas' 1.4 million undocumented residents weren't here, it would have cost the state $42 million in annual revenue and sapped $17.7 billion -- or 2 percent -- from Texas' yearly economic output.

In his letter, Gallego told Combs those numbers surely have grown since then.

"A more recent study from the Immigration Policy Center noted, '[i]f all unauthorized immigrants were removed from Texas, the state would lose $69.3 billion in economic activity, $30.8 billion in gross state product, and approximately 403,174 jobs, even accounting for adequate market adjustment time,' " it said.

In an interview Friday, Gallego said that he's not arguing that illegal immigration is a good thing, but that updated numbers would inform the debate that's taking place on Capitol Hill.

"There is a general perception that the people who are here are not here to work, they're here to be a drag on the economy," said Gallego, who represents much of El Paso's Lower Valley -- and 800 miles more of the U.S.-Mexico border. "I always believe that evidence matters."

"We will review Congressman Gallego's letter and send him a response," her spokesman, R.J. DeSilva, said in an email.

Combs' methods have come under fire.

In 2011, she predicted a $27 billion budget shortfall over the next two years. Her prediction prompted massive spending cuts -- including $5.4 billion from public education.

The shortfall mostly didn't materialize and in the legislative session that just ended, $3.9 billion in education spending was restored. Some lawmakers suspected that politics, not economics, guided Combs' 2011 projection.

Gallego, a 22-year veteran of the Legislature, didn't say anything about Combs' budgeting methodology, but he asked her to repeat Strayhorn's study of undocumented immigrants using the same methods.

"For the sake of consistency, I ask that you apply the same methodology used for the 2006 study and simply update the numbers," his letter said. "Your report would be vital to the 38 members of Congress from Texas, and to other elected officials and decision makers as they grapple with immigration reform. The study might also assist in shaping legislation related to immigration at the state and local levels."

Gallego said the Congressional Research Service could conduct such a study, but it would be much more superficial than the one done by Combs.

"The comptroller of public accounts for the state of Texas is the nerve center of state government," Gallego said.

The 2006 study said the state government was economically better off with its population of undocumented immigrants. But there were important caveats.

Unlike most other states, Texas does not have an income tax, so it loses less revenue than others do to illegal immigration.

"Whereas income taxes will miss much activity in an underground economy, a sales tax will more likely be collected no matter how one earns an income," the report said.

Also, the 2006 report said state coffers receive a net surplus from undocumented immigrants, but that doesn't count healthcare and jail costs that accrue to local governments.

"In fact, this report estimates the largest costs to local governments and hospitals; that is, incarceration and health-care costs," the report said. "The comptroller estimates costs of $1.3 billion for hospitals and $141.9 million for local incarceration attributed to undocumented immigrants."

Those expenses swamp the $42 million surplus the undocumented immigrants were estimated to bring in state revenue.

And, Gallego said, the report is silent on the human cost of a broken immigration system.

For example, there have been 5,000 cases in the United States in which citizen children were put up for adoption after their undocumented parents lost their rights and were deported. In some cases, the kids were put up for adoption even though they had family living legally in the United States, Gallego said.

"I think everyone agrees you have to have a process that works," he said. "We clearly do not have one that works."

The U.S. Senate is in the process of amending a comprehensive immigration-reform bill. Sen. Ted Cruz, R-Texas, last week said a bill favored by Democrats was likely to emerge.

That would send the fight to the Republican-controlled U.S. House of Representatives. Gallego predicted that a deal would emerge there as well.

"The House is a very difficult place," he said. "But at the end of the day, there's going to be a compromise that nobody's totally happy with."

Marty Schladen may be reached at mschladen@elpasotimes.com; 512-479-6606.